Hornby Colas Class 56:
Adding a sound system, driver, cab light and detonator flash LED
The real thing! Colas 56 with thanks to Kevin Bates........
Hornby's Colas Class 56 on the test track
Taking a look inside:
The un-powered fan assembly will have to be removed to make room for a speaker (screws already removed).
The Hornby lighting boards provide quite good relative lighting levels, so I'm hoping to use these without modification. Produced by Hornby, for a DCC ready locomotive, they are of course, wired with a common negative connection, which requires some interfacing circuitry, when driven from a standard DCC decoder.
I contemplated fitting independently controllable headlights, which could be switched off during yard movements, but it would involve removing and modifying the periscopic lightpipe used to route a proportion of the white directional LED light up through the headlight lens. Fair risk of collateral damage and not really much opportunity for yard movements with this loco, so on balance I've decided to keep it simple and run with Hornby's original optics.
There are two main contenders for the sound decoder:
1) ESU LokSound V4
2) Zimo MX645
These decoders are both capable of providing super smooth motor control and with a good speaker & an appropriate sound project on-board, can sound just like the real locomotive.
The function control and button mapping are quite different for the two decoder families, but they are both capable of fulfilling the lighting control requirements.
LokSound V4 Circuit diagram:
Zimo MX645 Circuit diagram
Good news! Paul Chetter's new Zimo "Protodrive" system has become available for Class 56, after very positive experience with this system on my three Zimo equipped Class 66 locos, this is my preferred approach for the 56 sound system!
The Hornby Class 56 has open mesh vents in the body sides immediately below the roof fan vents. This means that care is needed in the choice of speaker mounting technique, to avoid front to back cancellation effects.
The simplest approach seems to be to use a self contained speaker module. There is just room to accommodate a bass reflex speaker using a 20x40mm drive unit available from Digitrains..... so that is my first investment. Its only available as an 8 ohm unit rather than my normal 4 ohms types, so I hope it will be loud enough.
Simple plasticard supports keep the speaker clear of the flywheel.
To provide additional head height within the Hornby Class 56, I'm going to remove the original Hornby main PCB and replace it with a plasticard substrate, mounted lower down, between the original support pillars. I will glue sections of Maplin copper strip board to the ends of the substrate to act as anchor points. This technique worked well on my recently updated Class 31, which has an identical Main PCB.
Fan & main board removed, plasticard substrate glued in place and speaker resting on its support strips.
Speaker glued in, copper strip board added and wired ready for decoder connection.
Stay Alive Capacitor:
There is room to fit a 4700uF 16V capacitor between the new circuit assembly and the cab bulkhead. The Zimo MX645 includes a stay alive support circuit which enables 16V parts to be used safely..... so I've ordered some parts via Amazon. With an ESU LokSound solution, the capacitor is exposed to nearly the full rectified DCC track voltage, so 16V is a bit light..... I normally use 25V which is fine on my Lenz DCC powered set-up. However, a 4700uF cap rated at 25 volts would be a tight fit in the available space!
|A change of
circuit construction approach:
I've decided to try out the use of a Zimo adapter board "The ADAPLU". This provides solder pads for all decoder connections and a PluX-22 connector for the decoder unit. So if in the future I want to obtain a sound project update, I'll be able to extract the decoder without a soldering iron! It should make a neater job, with less wiring flapping around.
The ADAPLU adapter board mounted between the copper tag strips
The adaplu fully wired in. Great care is required to avoid shorts between the pads.
Close-up of the wired-in adapter board, with Zimo MX645 decoder plugged in.
Wiring the adaplu board up is not for the faint hearted, but the finished result is neater than my usual wired in decoder solutions and has the advantage that the decoder is easily removable.
Looking at the programming for the lights via Zimo's Swiss mapping:
Converting to actual CVs:
Set cab light on FO4 to "off when moving" CV130=60
Initial Function Mapping
All working fine!
Some adjustments to the motor control CVs:
The bass reflex speaker seems to have a fairly poor bass response:-( so I wired up an ESU 20x40mm speaker in a standard ESU enclosure via a change-over switch, to make a comparison...... I much prefer the sound quality from the ESU unit, which curiously seems to have a better bass response....... perhaps it actually lacks treble, which might produce a similar subjective effect? Either way, I need to find a way to accommodate the ESU unit. There is enough depth between roof and chassis block, but the enclosure is just too wide to fit between the pillars that handle the locomotive main fixing screws. However, the actual speaker is narrow enough to fit between them. So with a little careful surgery to the enclosure and some sealing compound to ensure all is finally air tight, I'm sure a solution, with the speaker venting directly out of the upper fan grills, is possible.....
The ESU speaker & enclosure are now in place and it's a small improvement, but I think the primary problem maybe that the speaker is directed upwards with the sound path straight through the fan mesh. I suspect this is adding emphasis to the higher frequencies, compared to my preferred fuel tank mounting method, where the sound is directed down towards the track and then reflected upwards. Hornby have filled the fuel tank with metal, so without some serious engineering work, that's not an option on the 56.
O.K. lets try a class 60 approach, with the ESU speaker enclosure mounted in the roof, but venting downwards, so that the sound escapes via the side grills...... Yes I think that is an improvement...... that's the configuration I will run with!
The final (?) solution.
(Despite appearances above, the speaker and enclosure are sealed and airtight.)
I think that'll do!
switch the headlights off when required:
The high intensity headlights are always switched off when the locomotive is manoeuvring within the yard, to avoid dazzling the staff at work there.
The Hornby model uses a common white LED to illuminate both the headlight and the marker lights at each end of the locomotive, via a pair of light pipes. In order to independently switch the headlight on and off, it will be necessary to remove part of the headlight light pipe and fit a dedicated headlight LED, beaming into the rear of the headlight lens (at each end of the loco).
The circuit would look something like this:
This arrangement simplifies operation by only needing the addition of "Headlights Disable" button to the Function list.
Looking at the Detail:
Underside of the cab, also showing the front markers light pipe
Cab removed, showing the location of the original LEDs
The headlight light pipe is "L-shaped" terminating in the round section lens.
The periscope part has to be removed in order to withdraw the rear light light pipe assembly.
To access the rear of the headlight lens, the marker and rear light light pipes need to be removed.
Take great care when extracting the transparent light pipes, they are very vulnerable at the rear of the lenses.
The remains of the light pipe have been cut off
....and a white chip LED is glued to the rear of the lens.
Blu Tack is used to prevent light from the new LED coupling into the windscreen transparency.
(This shot was taken at the other end of the loco, the temporary Blu Tack blobs at each side are simply holding the wires in place while glue dries.)
Finally the rear light and marker light pipes are refitted and the cab assembly is clipped back in place.
A few CV changes to add the new headlight disable function:
To assign button 0 to "Headlights disable" Swiss mapping group 7 is used as shown below:
Resulting in the following Function List: